Cam experts - help?

[withamc]

I put my Crane 2031 in this weekend. The problem I ran into was I couldn't quite get it to 0 lash, let alone .020-.060 preload - meaning I tightened the pedestal roller rockers down to 24 ft/lbs and I still had a little slop in the pushrod. I know this means I need longer pushrods.
Question One - How do I determine how long a pushrod I need? Where do I get them? PAW, where I got the cam, says it should work with the stock pushrods, they don't really seem to have a selection of additional lengths.
Question Two - I ran it for about 5 minutes before I decided it wasn't going to cut it. Will running it for five minutes like that damage anything? It was pretty noisy.

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86 GT, GT40P heads, Cobra cam, 1.7 RR's, Cobra intake, 65mm TB, 73mm Vortech, 24# injectors, MAC GT40P headers, 2-1/2" BBK H-pipe (w/cats), Flowmasters, 3.55s.
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Crane 2031 on order